04-16-2020, 11:59 AM
If the laptop cam with Win10, there's a good chance the only way to disable Secure Boot is from within Windows. If you try to change from UEFI to Legacy/CSM, I seem to recall Windows won't boot (i.e. you'd have to reinstall Windows to a Legacy/CSM formatted drive).
It sounds to me like for some reason the GRUB UEFI bits aren't being written to the disk. I don't know whether the efibootmgr utility (intro, man page) is available in the live installer but if it is you may be able to use it to find out more about what UEFI thinks is there to boot from (but be very careful trying to make changes with it!!).
USB sticks with GParted & Clonezilla may also make it easier to figure out what is on the drive vs what should be on the drive. The information in this blog post and linked from the Refind boot manager home page may help you figure out what needs to be done to get past your laptop's UEFI boot issue, though I appreciate that's a lot of reading.
I'm sorry I can't give more specific assistance - I've only fought one UEFI laptop and your problem seems quite different to mine.
It sounds to me like for some reason the GRUB UEFI bits aren't being written to the disk. I don't know whether the efibootmgr utility (intro, man page) is available in the live installer but if it is you may be able to use it to find out more about what UEFI thinks is there to boot from (but be very careful trying to make changes with it!!).
USB sticks with GParted & Clonezilla may also make it easier to figure out what is on the drive vs what should be on the drive. The information in this blog post and linked from the Refind boot manager home page may help you figure out what needs to be done to get past your laptop's UEFI boot issue, though I appreciate that's a lot of reading.
I'm sorry I can't give more specific assistance - I've only fought one UEFI laptop and your problem seems quite different to mine.